铀胁迫对反枝苋生理生化指标的影响分析

Effects of Uranium Stress on Physiological and Biochemical Index of Amaranthus retroflexus L.

为探究铀胁迫下富集植物反枝苋的抗逆机制及铀对反枝苋的毒理效应,通过盆栽控制性试验,研究了土壤不同浓度铀(U)胁迫(0、25、50、100、200、400 mg//kg)对反枝苋(Amaranthus retroflexus L.)叶片光合色素、蛋白质、丙二醛、脯氨酸含量和抗氧化酶(POD、CAT和SOD)活性的影响。结果表明:土壤铀胁迫对反枝苋叶片光合色素和蛋白质含量表现出低促高抑,25 mg/kg处理下叶绿素a、叶绿素b和蛋白质含量显著高于对照;中低浓度下,抗氧化酶系统被激活,活性显著高于对照,有效清除活性氧自由基;100 mg/kg处理时,SOD活性率先降低,引起CAT和POD活性出现无底物性下降;200、400 mg/kg胁迫下植物产生并积累了大量的自由基,超过了SOD、CAT、POD的清除能力,致使酶活性降低,膜脂过氧化程度加深,MDA含量激增;各处理下脯氨酸含量均显著高于对照,使植物在高胁迫下抗氧化酶系统遭到破坏后仍能起到抗铀胁迫作用。

Amaranthus retroflexus has strong enrichment ability of the uranium in soil. Biological markers including plant photosynthetic pigments,soluble protein,superoxide dismutase（SOD）,peroxidase（POD）,catalase（CAT）,malondialdehyde（MDA）and proline（pro）of Amaranthus retroflexus L. were discussed in different uranium concentrations of 0,25,50,100,200,400 mg/kg,to explore the tolerance of hyperaccumulator Amaranthus retroflexus of uranium stress and uranium stress on plant toxicology effects. Result showed that the effects of U treatment on the photosynthetic pigments and protein showed hormesis effect. Under the uranium concentration of 25 mg/kg,the increase of plant pigments and soluble protein was significant,and under higher concentration reduced soon. Antioxidant enzyme system was activated by low uranium level,effectively removed active oxygen radicals. SOD activity was firstly reduced under 100 mg/kg uranium stress,which leaded to the decrease of POD and CAT under the uranium concentrations of 200 mg/kg. A large amount of active oxygen radicals were compounded and accumulated,over the removal ability of SOD,POD and CAT under the high level of uranium concentration. This caused the decrease of enzyme activity and the damage of the cell membrane,resulting in the rise of MDA contents rapidly. Proline contents under different uranium stresses were significantly higher than the control. Prolinebecame the primary protection material when antioxidant enzyme system was damaged under high uranium concentrations.